A turn on ESIPT probe for rapid and ratiometric fluorogenic detection of homocysteine and cysteine in water with live cell-imaging

5(Benzothiazol-2-yl)-4-hydroxyisophthalaldehyde (BHI), an intense ESIPT containing molecule in mixed media loses its properties due to resonance-assisted H-bond (RAHB) in absolute water. Due to resonance-assisted H-bond the o-aldehyde is more reactive than the other one. With addition of cysteine/homocysteine into this solution the o-aldehyde group gets transformed into thiazolidine/thiazine ring, respectively, and the phenolic proton becomes free enough for transfer to nitrogen of the benzothiazole ring in excited state, that is, the ESIPT of BHI is turned on. Thus we can detect cysteine/homocysteine in water as well as in live cells.     

A validated HPLC‐fluorescence method with a semi‐micro column for routine determination of homocysteine,cysteine and cysteamine,and the relation between the thiol derivatives in normal human plasma

A semi‐micro column HPLC‐fluorescence method for routine determination of thiol derivatives such as homocysteine (Hcy), cysteine (Cys) and cysteamine (CA) is described. The thiol derivatives labeled with ammonium‐7‐fluorobenzo‐2‐oxa‐1,3‐diazole‐4‐sulfonate (SBD‐F) were isocratically separated within 12 min on a semi‐micro ODS column (Daisopak‐SP‐120‐5‐ODS‐BP) with a mixture of 25 mm acetate buffer (pH 2.00) and CH₃CN as a mobile phase. The purity and similarity of SBD‐thiols by a multi‐wavelength fluorescence detector were more than 92.3 and 96.7%. The detection limits of Hcy, Cys and CA at a signal‐to‐noise ratio of 3 were 0.16, 0.47 and 0.03 µm , respectively. Furthermore validation parameters such as accuracy, precision and robustness of the proposed method showed satisfactory results. Almost 850 plasma sample injections (range 572–1076, n = 3) for a column could be performed without differences in retention time and peak heights of labels. As an application of the proposed method, the determination of thiol derivatives in normal human plasma (n = 103) was demonstrated. The correlation coefficients between Hcy vs Cys and Hcy vs CA were 0.38 and −0.35, respectively. Copyright © 2009 John Wiley & Sons, Ltd.     

Induction of tissue inhibitor of matrix metalloproteinase-2 by cholesterol depletion leads to the conversion of proMMP-2 into active MMP-2 in human dermal fibroblasts

Cholesterol is one of major components of cell membrane and plays a role in vesicular trafficking and cellular signaling. We investigated the effects of cholesterol on matrix metalloproteinase-2 (MMP-2) activation in human dermal fibroblasts. We found that tissue inhibitor of matrix metalloproteinase-2 (TIMP-2) expression and active form MMP-2 (64 kD) were dose-dependently increased by methyl-β-cyclodextrin (MβCD), a cholesterol depletion agent. In contrast, cholesterol depletion-induced TIMP-2 expression and MMP-2 activation were suppressed by cholesterol repletion. Then we investigated the regulatory mechanism of TIMP-2 expression by cholesterol depletion. We found that the phosphorylation of JNK as well as ERK was significantly increased by cholesterol depletion. Moreover, cholesterol depletion-induced TIMP-2 expression and MMP-2 activation was significantly decreased by MEK inhibitor U0126, and JNK inhibitor SP600125, respectively. While a low dose of recombinant TIMP-2 (100 ng/ml) increased the level of active MMP-2 (64 kD), the high dose of TIMP-2 (≥ 200 ng/ml) decreased the level of active MMP-2 (64 kD). Taken together, we suggest that the induction of TIMP-2 by cholesterol depletion leads to the conversion of proMMP-2 (72 kD) into active MMP-2 (64 kD) in human dermal fibroblasts.     

A practical and efficient method to calculate AIM localization and delocalization indices at post-HF levels of theory

A practical and efficient method is proposed for calculating localization and delocalization indices at post-Hartree-Fock levels, and the method is tested at the CISD/6-311G++(2d, 2p) level for a large set of molecules. Our method, which utilizes wave functions written in the natural molecular orbital format and obtained with GAUSSIAN 94 or GAUSSIAN 98, convincingly extends the concepts established at the HF level.     

Quantitative determination of BMS-378806 in human plasma and urine by high-performance liquid chromatography/tandem mass spectrometry

BMS-378806 is a human immunodeficiency virus (HIV) entry inhibitor that is being developed for the oral treatment of HIV infection. Human plasma and urine LC/MS/ MS methods have been developed and validated for the quantitation of BMS-378806. For human plasma method, methyl t-butyl ether was used to extract BMS-378806 from plasma in a 96-well format, and the organic layers were dried down and then reconstituted for the injection, while a dilute-and-shoot approach was used for human urine method in a 96-well format. Chromatographic separation was achieved isocratically on a Phenomenex C18 (2) Luna column (2 x 50 mm2, 5 microm). The mobile phase contained 60:40 v/v of 0.1% formic acid in water and ACN. Detection was by positive ion electrospray MS/MS. The standard curves ranged from 1.25 to 1000 ng/mL for the plasma assay and from 10 to 5000 ng/mL for the urine assay. The curves were fitted to a 1/x2 weighted quadratic regression model for both methods. The validation results demonstrated that both methods had satisfactory precision and accuracy across the calibration ranges. The methods were applied to the analysis of human plasma and urine samples from a single ascending dose clinical study to assess the pharmacokinetics of the drug. The pharmacokinetic analysis results indicated the absorption and disposition of the drug was rapid. The systemic exposure of BMS-378806 was generally dose proportional among the doses from 100 to 1200 mg, but not dose proportional to 1600 mg. There were modest increases in the systemic exposure when the drug was given with food or given as a solution formulation. Renal excretion was not a substantial elimination pathway of the drug. BMS378806 was safe and well tolerated over a dose range of 100-1600 mg administered as a single oral dose.     

Quantitative evaluation of specific and nonspecific interactions in radical exchange between phenyllithium and bromobenzene

The results of kinetic studies on the exchange of radicals between PhLi and PhBr in variuos binary pentane-ether mixtures in the presence of alkaline metal halides were discussed. The nucleophilicity of the ethers and metal halides, which is a quantitative measure of their influence on the exchange reaction, was determined. The specific and nonspecific components of coordination were identified and quantitatively evaluated for some parameters of the exchange reaction.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 272–275, February, 1995.     

Chemical Stability Study of H1 Antihistaminic Drugs from the First and the Second Generations,Diphenhydramine, Azelastine and Bepotastine,in Pure APIs and in the Presence of Two Excipients,Citric Acid and Polyvinyl Alcohol

The chemical stability of diphenhydramine (DIPH), azelastine (AZE) and bepotastine (BEPO) was examined in solutions and solids. The drugs were subjected to high temperature (70 °C for 35 h) or UV/VIS light (18.902–94.510 kJ/m²) at pH 1–13, to examine their percentage degradation and kinetics of degradation. Further, the stability of solid DIPH, AZE and BEPO was examined in the presence of excipients of different reactivity, i.e., citric acid (CA) and polyvinyl alcohol (PVA) under high temperature/high humidity (70 °C/80% RH) or UV/VIS light (94.510 kJ/m²). Under high temperature, DIPH degraded visibly (>19%) at pH 1 and 4, AZE was shown stable, while the degradation of BEPO was rather high (>17%) in all pH conditions. Under UV/VIS irradiation all the drugs were shown labile with degradation in the range 5.5–96.3%. As far as the solid mixtures were concerned, all drugs interacted with excipients, especially under high temperature/high humidity or UV/VIS light. As a result, DIPH, AZE and BEPO were compared in terms of their stability, with regard to their different structures and acid/base properties. All these results may be helpful for manufacturing, storing and applying these drugs in their topical (skin, nasal and ocular), oral and injectable formulations.     

Hydrolytic degradation of poly[(4,4′-oxydiphenylene)pyromellitic amido acid] in concentrated sulphuric acid and in dimethylformamide via hydrodynamic investigations

Translational diffusion and viscosity measurements were performed for poly[(4,4′-oxydiphenylene)pyromellitic amido acid] in DMF, LiCl/DMF, and 96% H₂SO₄ solutions to characterise the rate of the polymer degradation in 96% H₂SO₄ in comparison with its relative stability in organic solutions. The hydrodynamic data were obtained in different stages of hydrolytic polymer degradation at various temperatures from 20 to 80 °C. The mechanism of the degradation is discussed as well as the possibility of molecular investigations of the polymer under conditions of quasi-stable solution.     

Composition of aromatic products in the catalytic degradation of the mixture of waste polystyrene and high-density polyethylene using spent FCC catalyst

In this chemical recycling process, spent FCC catalyst used had an advantage with an economical and environment aspect, such as a low catalyst price in liquid-phase reaction and a reuse of waste catalyst. The characteristics of oil product and its aromatic product distribution, as a function of reaction time in the reactor and also proportion of HDPE and PS in the mixture, were compared. Main products obtained were light hydrocarbons within the gasoline range that were mainly produced during initial reaction time. The formation of aromatic products such as styrene and ethylbenzene as major components depended appreciably on the reaction time, as well as the composition of HDPE and PS in the mixture used for degradation. For the distribution of C₉-C₁₂ alkylaromatic components as by-products, methylstyrene (C₁-styrene) and isopropylbenzene (C₃-benzene) components were the main products formed by β-scission and hydrogen transfer of PS, while the rest of alkylaromatic products showed very low fraction being 1% or less.     

Designing Novel Strategy to Produce Active Nanohybrids in Sunlight for Purification of Water Based on Inorganic Nanolayers,Magnetic Nanocomposites and Organic Species

Energy and water related problems have attracted strong attention from scientists across the world because of deficient energy and water pollution. Following this line, new strategy depended on preparing nanolayers of Al/Zn and magnetic nanoparticles of cobalt iron oxides nanocomposite in addition to long chains of hydrocarbons of stearic acid to be used as roofs, fillers and pillars; respectively, to design optical-active nanohybrids in sunlight for removing the colored pollutants from water in few minutes. By using long chains of hydrocarbons of stearic acid, X-ray diffraction (XRD) results and TEM images showed expansion of the interlayered spacing from 0.76 nm to 2.02 nm and insertion of magnetic nanoparticles among the nanolayers of Al/Zn. The optical properties and activities showed that the nanohybrid structure based on zinc oxide led to clear reduction of the band gap energy from 3.3 eV to 2.75 eV to be effective in sunlight. Photocatalytic degradation of the dye of acid green 1 confirmed the high activity of the prepared zinc oxide nanohybrids because of a complete removal of the dye after ten minutes in sunlight. Finally, this strategy was effective for producing photo-active nanohybrids for using renewable and non-polluting energy for purifying water.     

Quantitative analysis of biodiesel in blends of biodiesel and conventional diesel by comprehensive two-dimensional gas chromatography and multivariate curve resolution

In this paper, a method to determine the composition of blends of biodiesel with mineral diesel (BXX) by multivariate curve resolution with Alternating Least Squares (MRC-ALS) combined to comprehensive two-dimensional gas chromatography with Flame Ionization Detection (GC × GC-FID) is presented. Chromatographic profiles of BXX blends produced with biodiesels from different sources were used as input data. An initial evaluation carried out after multiway principal component analysis (MPCA) was used to reveal regions of the chromatograms were the signal was likely to be dependent on the concentration of biodiesel, regardless its vegetable source. After this preliminary step MCR-ALS modeling was carried out only using relevant parts of the chromatograms. The resulting procedure was able to predict accurately the concentration of biodiesel in the BXX samples regardless of its origin.     

Tunneling and quantum localization in chaos‐driven symmetric triple well potential: An approach using quantum theory of motion

For a symmetric triple well potential, driven by the forces associated with the bifurcation diagram of a logistic map, the tunneling and quantum localization are studied using quantum theory of motion and time‐dependent Fourier grid Hamiltonian methods. Detailed analysis reveals that application of only asymmetric or symmetric perturbation results into either quantum localization or over‐barrier transition and no tunneling while application of mixed symmetry perturbation gives either tunneling or over‐barrier transition, depending on temporal nature and initial position of the particle. For bifurcative and chaotic symmetric‐asymmetric perturbation, with truncation of mixed symmetry perturbation, a sudden jump in energy causes a transition from the tunneling phenomenon to the over‐barrier transition. With particle located initially near to either of the minima of the unperturbed well, quantum localization, or over‐barrier transition is observed, depending on types of perturbation used.     

Evaluation of Philips and Ziegler-Natta high-density polyethylene degradation during processing in an internal mixer using the chain scission and branching distribution function analysis

The oxidative and thermo-mechanical degradation of HDPE was studied during processing in an internal mixer under two conditions: totally and partially filled chambers, which provides lower and higher concentrations of oxygen, respectively. Two types of HDPEs, Phillips and Ziegler-Natta, having different levels of terminal vinyl unsaturations were analyzed. Materials were processed at 160, 200, and 240 °C. Standard rheograms using a partially filled chamber showed that the torque is much more unstable in comparison to a totally filled chamber which provides an environment depleted of oxygen. Carbonyl and transvinylene group concentrations increased, whereas vinyl group concentration decreased with temperature and oxygen availability. Average number of chain scission and branching (n_s) was calculated from MWD curves and its plotting versus functional groups' concentration showed that chain scission or branching takes place depending upon oxygen content and vinyl groups' consumption. Chain scission and branching distribution function (CSBDF) values showed that longer chains undergo chain scission easier than shorter ones due to their higher probability of entanglements. This yields macroradicals that react with the vinyl terminal unsaturations of other chains producing chain branching. Shorter chains are more mobile, not suffering scission but instead are used for grafting the macroradicals, increasing the molecular weight. Increase in the oxygen concentration, temperature, and vinyl end groups' content facilitates the thermo-mechanical degradation reducing the amount of both, longer chains via chain scission and shorter chains via chain branching, narrowing the polydispersity. Phillips HDPE produces a higher level of chain branching than the Ziegler-Natta's type at the same processing condition.     

Adsorptive stripping voltammetric determination of the anti-inflammatory drug celecoxib in pharmaceutical formulation and human serum

Celecoxib is a cyclooxygenase inhibitor, that has been recently and intensively prescribed as an anti-inflammatory drug in rheumatic osteoarthiritis. A robust, highly reliable and reproducible square-wave (SW) adsorptive cathodic stripping voltammetric procedure was developed for the determination of celecoxib in pharmaceutical formulation and human serum. The analytical procedure was based on the reduction of the CN of the pyrazole ring of the drug molecule at the mercury electrode surface in Britton-Robinson buffer of pH 7.0. The SW adsorptive cathodic stripping voltammogram of celecoxib showed a single well-defined peak at −1.54 V (vs. Ag/AgCl/KCl_s) using an accumulation potential of −0.70 V, frequency of 120 Hz, scan increment of 10 mV and pulse amplitude of 25 mV. Repeatability was examined for 1×10⁻⁸ M CXB drug solution after 30 s pre-concentration and a mean recovery of 99.4±0.4% (n=5) was achieved. For 90 s preconcentration, a linear concentration range of 1×10⁻⁹-2×10⁻⁸ M CXB and a detection limit of 1.86×10⁻¹⁰ M were achieved. The proposed procedure was successfully applied for the determination of the drug in capsules and human serum with mean recoveries of 101.5±0.6 and 98.8±1.1%, respectively. A detection and quantitation limits of 1.0×10⁻⁹ M (0.4 ng ml⁻¹) and 4.7×10⁻⁹ M (1.3 ng ml⁻¹) were achieved for the determination of the drug in human serum. Moreover, the procedure was useful for study of the pharmacokinetic profile of celecoxib in a healthy volunteer after administration of a single oral dose (celebrex®, 200 mg).     

Determination of acetylsalicylic acid and salicylic acid in blood and plasma by HPLC

A method is described for the determination of acetylsalicylic acid and salicylic acid in human whole blood and plasma which uses liquid chromatography with UV detection. The enzymatic degradation of acetylsalicyclic acid in blood and plasma is examined. Addition of potassium fluoride as enzyme inhibitor and deep freezing after plasma preparation allows storage of plasma for one week. A mixture of acetonitrile and diluted acetic acid as mobile phase give the best peak shape. Traces of iron lead to slight peak broadening; addition of EDTA results in excessive tailing. The detection limit for acetylsalicylic acid and salicylic acid is about 250 ng/ml for a 1.0 ml primary sample. The method is sensitive enough for the monitoring of both drugs in bioavailability studies.     

Concentration profiles of cocaine, pyrolytic methyl ecgonidine and thirteen metabolites in human blood and urine: determination by gas chromatography-mass spectrometry

When cocaine is smoked, a pyrolytic product, methyl ecgonidine (anhydroecgonine methyl ester), is also consumed with the cocaine. The amount of methyl ecgonidine formed depends on the pyrolytic conditions and composition of the illicit cocaine. This procedure describes detection of cocaine and 10 metabolites--cocaethylene, nor-cocaine, nor-cocaethylene, methyl ecgonine, ethyl ecgonine, benzoylecgonine, nor-benzoylecgonine, m-hydroxybenzoylecgonine, p-hydroxybenzoylecgonine and ecgonine--in blood and urine. In addition, the detection of pyrolytic methyl ecgonidine and three metabolites--ecgonidine (anhydroecgonine), ethyl ecgonidine (anhydroecgonine ethyl ester) and nor-ecgonidine (nor-anhydroecgonine)--are included. The newly described metabolites, ethyl ecgonidine and nor-ecgonidine, were synthesized and characterized by gas chromatography-mass spectrometry (GC-MS). All 15 compounds were extracted from 3 mL of blood or urine by solid-phase extraction and identified by a GC-MS method. The overall recoveries were 49% for methyl ecgonine, 35% for ethyl ecgonine, 29% for ecgonine and more than 83% for all other drugs. The limits of detection were between 0.5 and 4.0 ng/mL except for ecgonine, which was 16 ng/mL. Linearity for each analyte was established and in all cases correlation coefficients were 0.9985-1.0000. The procedure was applied to examine the concentration profiles of analytes of interest in post-mortem (PM) blood and urine, and in urine collected from living individuals (LV). These specimens previously were shown to be positive for the cocaine metabolite, benzoylecgonine. Ecgonidine, the major metabolite of methyl ecgonidine, was present in 77% of PM and 88% of the LV specimens, indicating smoking as the major route of cocaine administration. The new pyrolytic metabolites, ethyl ecgonidine and nor-ecgonidine, were present in smaller amounts. The urine concentrations of nor-ecgonidine were 0-163 ng/mL in LV and 0-75 ng/mL in PM specimens. Ethyl ecgonidine was found only in PM urine at concentrations 0-39 ng/mL. Ethanol-related cocaine metabolites, ethyl ecgonine or cocaethylene, were present in 69% of PM and 53% of cocaine-positive LV specimens, implying alcohol consumption with cocaine use. The four major metabolites of cocaine--benzoylecgonine, ecgonine, nor-benzoylecgonine and methyl ecgonine--constituted approximately 88 and 97% of all metabolites in PM and LV specimens, respectively. The concentrations of nor-cocaine and nor-cocaethylene were consistently the lowest of all cocaine metabolites. At benzoylecgonine concentrations below 100 ng/mL, ecgonine was present at the highest concentrations. In 20 urine specimens, benzoylecgonine and ecgonine median concentrations (range) were 54 (0-47) and 418 ng/mL (95-684), respectively. Therefore, detection of ecgonine is advantageous when benzoylecgonine concentrations are below 100 ng/mL.     

Evidence of steric factors in the fungitoxic mechanisms of 8-quinolinol and its 2-, 3-, 4-, 5-, 6-and 7-chloro and bromo analogues

Summary A study was made of the fungitoxicity of 2-, 3-, 4-, 5-, 6- and 7-chloro and bromo-8-quinolinols againstAspergillus niger,A. oryzae,Myrothecium verrucaria,Trichoderma viride andTrichophyton mentagrophytes in Sabouraud dextrose broth and in Yeast Nitrogen Base supplemented with 1%D-glucose and 0.088%L-asparagine. Based on the presence or absence of synergism between pairs of substituted 8-quinolinols and reversal or nonreversal of toxicity byL-cysteine or N-acetyl-L-cysteine, the following conclusions were reached: (1) substituents on the quinoline ring change the site(s) of action of the toxicant; (2) the sites of action of the 5-, 6-, and 7-chloro-8-quinolinols are different from each other and from 8-quinolinol and its 2-, 3-, and 4-chloro analogues, and the same is true for the corresponding bromo compounds; (3) 8-quinolinol and its 3- and 4-chloro and bromo analogues appear to share common sites of action; (4) for good antifungal activity the 2 position of the ring must not be substituted by sterically bulky groups; (5) the geometry of the binding sites of action are not so constrained that they cannot accommodate the analogously substituted chloro- and bromo-8-quinolinols.

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Nachweis sterischer Faktoren bei der Fungitoxizität von 8-Chinolinol und seinen 2-, 3-, 4-, 5-, 6- und 7-Chlor- und -Brom-Analogen

Zusammenfassung Es wurde eine Studie der Fungitoxizität von 2-, 3-, 4-, 5-, 6- und 7-Chlor- und-Brom-8-chinolinol gegenüberAspergillus niger,A. oryzae,Myrothecium verrucaria,Trichoderma viride undTrichphyton mentagrophytes in Sabouraud Dextrose Nährmedium und in Hefe-N-Base mit 1%D-Glucose und 0.088%L-Asparagin unternommen. Auf der Basis des Zutreffens oder der Abwesenheit eines Synergismus zwischen Paaren von substituierten 8-Chinolinolen und der Umkehrung oder Nichtumkehrung der Toxizität durchL-Cystein oder N-Acetyl-L-cystein wurden folgende Schlußfolgerungen abgeleitet: (1) Substituenten am Chinolin-Ring ändern die Aktionsstelle(n) des Toxikans; (2) Die Angriffsstellen der 5-, 6- und 7-Chlor-8-chinolinole sind untereinander und von 8-Chinolinol und seinen 2-, 3- und 4-Chlor-Analogen verschieden, wobei das auch für die entsprechenden Brom-Verbindungen gilt; (3) 8-Chinolinol und seine 3- und 4-Chlor- und -Brom-Analogen scheinen gemeinsame Aktionsstellen zu teilen; (4) für eine gute antifungale Aktivität darf die 2-Position des Rings nicht mit sterisch anspruchsvollen Gruppen besetzt sein; (5) Die Geometrie des Bindungsstellen der Wirkung ist nicht so gespannt, daß nicht sowohl analoge Chlor- oder Brom-8-chinolinole Platz finden.

     

Liquid chromatographic determination of dimethadione and trimethadione in human serum on octadecyl treated microporous glass columns

Summary The liquid chromatographic determination of trimethadione (TMO) and its methabolite, dimethadione (DMO) were studied by high-performance liquid chromatography (HPLC) on octadecyl-modified microporous glasses, prepared with toluene solution containing octadecyl-dimethylchlorosilane, using two types of microporous glass with various mean pore diameters and/or specific surface areas. Using acetonitrile-water mixtures as eluents, TMO and DMO in human serum were separated on the glasses studied, but with different degrees of resolution. In this present study, we report the development of a rapid and selective HPLC method for the simultaneous analysis of TMO and DMO in human serum.